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Sunday, July 31, 2011

Throughout the day, major changes have taken place in the forecast for this week both for the area and in the tropics, which have made the update planned for this evening invalid. A full, detailed discussion will be posted tomorrow morning discussing these changes in more details, and a brief summary of these changes has been posted below:

Tomorrow: Strong to potentially thunderstorms are expected tomorrow afternoon and evening. A cold front which was previously expected to be weak and dry has trended stronger with more moisture and better parameters, which will result in a risk of severe weather. Bulk shear is much lower, however, which may limit the intensity and coverage area of tomorrow's storms, but mid level lapse rates are much more supportive of severe weather.

Storms should affect the area tomorrow afternoon, and while the storms won't be as intense or anywhere near as widespread as Friday's storms, scattered storms are expected, and some of these could become strong or severe, producing small hail and gusty winds, with at least a 15% risk of severe weather expected at this time. Tomorrow morning's update will include a severe weather risk map.

Wednesday: Some models are showing a strong low pressure affecting the area on Wednesday, bringing a risk of strong to severe thunderstorms, others show the low pressure to the south of the area bringing a chilly heavy rain for NYC, and others only show a weak low pressure with isolated storms. The scenario where the storm tracks to the south of the area is less likely at this time, though there is still a good amount of uncertainty regarding which of the two other scenarios verify. Due to high bulk shear, however, should we see a low pressure to the north of the area, there could be a more widespread severe weather outbreak. Tomorrow morning's update will discuss this in more details.

Tropics: Invest 91L was originally expected to develop today or tomorrow, but throughout the day, it has split and become much less organized. As a result, both the forecast development time frame and the track of 91L have changed. Stay tuned for an update tomorrow morning in the Tropics page for the new forecast for 91L.

Saturday, July 30, 2011

Note: Due to some difficulties with the internet connection, the blog was not updated from this morning through this evening. Tonight's update includes an updated 5-Day Forecast for NYC and an updated Tropics page, and an update on the hurricane season outlook as well as a brief August outlook will be posted tomorrow in the Long Range Forecasts page as well as an updated 5-Day Forecast for the rest of the area.

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After yesterday's widespread strong to severe thunderstorms, today brought a much more quiet day across the region, with mostly sunny skies and less humidity. High temperatures were slightly warmer, however, reaching the upper 80s inland, lower to mid 90s in the immediate NYC area, and the upper 80s to lower 90s in Long Island and southern Connecticut. The warmth will continue over the next few days, with Monday the warmest day, but after Monday, temperatures are expected to begin cooling down, and the potential is there for storms to affect the area on Monday, Wednesday and Thursday.

Tomorrow's Outlook:

Tomorrow will bring mostly sunny skies to the area along with slightly cooler temperatures. Temperatures are expected to reach the mid to upper 80s inland, upper 80s to lower 90s in the immediate NYC area, and with a west/WSW wind expected, Long Island and southern Connecticut will see highs in the mid to upper 80s.

Next Week: Warm, Then Slightly Colder

A low pressure in Canada will bring the next cold front into the area on Monday. With a slightly warmer air mass ahead of the front, temperatures will warm up as well, reaching the upper 80s to lower 90s inland, lower to mid 90s in the immediate NYC area, and due to a west/WSW wind, Long Island/S CT will reach the upper 80s to lower 90s with the exception of the immediate southern coast of long Island, which will stay cooler. Isolated thunderstorms are expected with the front on Monday evening, but widespread thunderstorms are not expected from this cold front.

The cold front is now expected to bring in a stronger cold air mass than previously thought. Most of the models have trended stronger with the Canadian low pressure, and now show a stronger trough moving into the Northeast on Tuesday. While this will not bring a significantly colder air mass into the area, temperatures will slightly cool down, reaching the mid to upper 80s across most of the area.

More uncertainty returns into the forecast on Wednesday, when a low pressure is expected to approach the region. Most of the models agree with showing a low pressure moving through the area on Wednesday night, bringing cooler temperatures for Wednesday/Thursday along with locally heavy rainfall. Some of the models may be overdoing the intensity and extent of the rainfall, and at this time, while some rain is expected across the area, it is expected to be more scattered, not a part of a large rain system. There is some uncertainty with the temperatures, though at this time I put temperatures in the mid to upper 80s from NYC and further west for both of these days, with high temperatures potentially reaching the lower 90s in the immediate NYC area on Wednesday.

The unsettled weather is expected to temporarily end around Friday, with drier conditions returning along with temperatures in the mid to upper 80s across most of the area. Beyond Friday, there is increasing uncertainty as some models show dry conditions, while others show rain and clouds through parts of the weekend. More information will be posted on next weekend once details become clearer.

Friday, July 29, 2011

Below, short term updates will be posted on the severe storms that will affect the area this afternoon and evening.

**Forecast graphics will be posted with each update. Click on the images to view them in a larger size.**

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7:45 PM: Most of the storms have ended across the area, but there is still some activity east of NYC. There is a strong storm near Bronx moving SE, towards northern Nassau. Another severe storm producing heavy rain and strong wind gusts is near central Nassau moving east, towards western Suffolk, and there is a strong thunderstorm with heavy rain affecting JFK airport.

This is the last storm update for tonight. Due to the storm updates, no discussion on the upcoming weather will be posted tonight. Instead, the typical evening update will be posted tomorrow morning, with updates to the 5-Day Forecast, Tropics page, Long Range Outlooks, and the Storm Summary pages during the rest of the day tomorrow.

7:20 PM:Warning:A severe thunderstorm capable of producing small hail and strong wind gusts up to 60 mph is currently over Union city, and will enter central/southern Manhattan (34th street and further south) within the next 10 minutes. This storm will then enter Queens within the next 15 minutes.

6:50 PM:**Tornado Warning is still in effect for Westchester county.**

The severe storm capable of producing a tornado is currently near Port Chester, NY, and is moving southeast. Some weakening of this cell is expected as it moves through the Long Island sound into a more stable air mass, but rotation may still persist once it crosses the sound. Places that will be affected by this cell within the next 1/2 hour are NE Nassau and NW Suffulk counties. Towns/cities in these areas include Bayville, Oyster Bay, Syosset, and Huntington.

Looking across the rest of the area, there is a heavy thunderstorm in central Bergen county moving east, towards southern Westchester. Another strong storm in eastern Morris county is moving ESE, towards Clifton and Fort Lee, later on moving into northern Manhattan. There is another strong storm near northwestern Passaic moving ESE, towards northern Bergen county. The last storm recently formed in eastern Union county, and is moving towards Staten Island and Brooklyn.

6:15 PM:**Tornado Warning is in effect for Westchester county.**

Widespread severe storms are currently affecting the area, with some of them producing rotation. The most intense storm is near Ossining, NY, and is moving SE. Places directly in the path of this possible tornado include White Plains and Port Chester.

Another severe storm with weak rotation is near the border of Sussex/Orange counties and is moving ESE, right along the border. This storm will affect places along the NY/NJ border over the next 1/2 hour. A severe storm in southern Sussex county capable of producing gusty winds and small hail is moving ESE as well, and will affect northern Morris, East Passaic, and southern Bergen counties.

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4:00 PM: Storms Starting To Fire Up

Since this morning, the western half of the area began to destabilize with some clearing in the cloud cover. Most places west of NYC are seeing partly to mostly cloudy skies, with mostly cloudy skies in NYC and cloudy skies in Long Island/S CT, where temperatures are much colder, in the lower to mid 70s in southern Connecticut and the mid 70s to lower 80s in Long Island. While Long Island/S CT are under a stable air mass, places from NYC and further west are seeing more instability, with lift index values between -4 and -7, CAPE between 1000-2500, and bulk shear between 40-50 knots. Lower lift index values support a higher severe weather risk, and higher CAPE/bulk shear support a better severe weather risk.

The parameters above support at least a 30% risk of severe weather, where severe storms would be capable of producing strong to damaging wind gusts, hail, heavy rainfall, and an isolated tornado or two. As we have seen many times, however, the parameters alone don't determine if we see severe weather or not, as it is possible that severe storms just north or south of the area prevent storms from developing/persisting over the area.

Possible Storm Scenarios: As of now, we are seeing a severe storm in northeastern Pennsylvania moving ESE, which would take it into Orage and Rockland counties, and an area of strong thunderstorms in east central PA, moving towards places directly west and south of NYC. Every short range model showed this storm where it is now, then forming a line of severe storms extending further south, resulting in a widespread area of severe thunderstorms moving through most of northern NJ, SE NY and NYC between 6-10 PM tonight, producing heavy rainfall, strong wind gusts, smaill hail, and an isolated tornado.

The scenario mentioned above is a reasonable solution. It is possible, however, that storms fail to form south of the NE PA cell, and northern New Jersey/NYC would stay dry, missing today's storms. At this time, looking at the latest radar, there is no indication of additional storms forming in between the isolated cells near Allentown and the severe cell in northern PA, and that area will be monitored over the next 1-2 hours as it will determine whether NYC/N NJ see severe storms or only isolated storm activity.

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11:00 AM: Severe Storms This Evening

The area is currenly seeing mainly cloudy skies after a round of showers and thunderstorms moved through northern NJ/NYC last night, bringing rainfall amounts up to 1/4 inch. This is just the first round of today's storms, as more widespread severe weather will affect the region, including the area, this evening. With the last widespread rain event, on July 25, the warm front was stuck to the west of the area, keeping us stuck with cloudy skies and non-severe rain and thunder. Today's scenario is different, however, as the warm front has already passed NYC, and is currently near central New England. As a result, today will bring more instability and a bigger risk of severe weather.

This Afternoon: While the area is currently under mainly cloudy skies, clearing in the cloud cover is expected around 12-2 PM, with mostly to partly sunny skies from NYC and further west. With the warm front still stuck in the eastern parts of the area, however, most of Long Island and southern Connecticut will see mostly cloudy to cloudy skies. With the break in the cloud cover, temperatures west of NYC will quickly warm up into the upper 80s to lower 90s, and a few mid 90s may be possible in NE NJ. Combined with the humidity, as dew points will be in the lower 70s, the heat index will reach the 96-100 degree range in NYC later this afternoon.

Evening / Overnight: The cold front will then approach the area overnight, bringing more widespread storms. The most widespread storms should stay in New York, where heavy rain and thunderstorms are expected, but as there will be instability in the area, there is a better risk of severe storms. Thunderstorms should start to form in SE NY/NE Pennsylvania late this afternoon, and move into the area in the evening hours, between 6 PM and 11 PM. These storms will be capable of producing strong wind gusts, small hail, and heavy rainfall with localized flash flooding possible. Stay tuned for storm updates this afternoon and evening.

Thursday, July 28, 2011

Reminder: For information about Tropical Storm Don, please refer to the "Tropics" page. Updates on Don are being posted twice a day.

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Tomorrow's Storm Risk:

Tomorrow will bring a slight risk of severe weather. A warm front currently over Pennsylvania will cross the area tomorrow morning, bringing more instability into the area by the afternoon and evening hours. Most of the storms tomorrow evening are likely to stay to the north of the area, but some storms are expected to affect the area as well, especially from NYC and further north. Any storm that reaches the area will be capable of becoming severe. It is possible, however, that the severe weather may need to be shifted further north and away from NYC, and more information on tomorrow's severe weather risk will be posted tomorrow morning.

Temperatures will be warm tomorrow as well. Mostly cloudy skies are expected, but with a warm air mass, temperatures will still warm into the upper 80s to lower 90s from NYC and further west, and if there is enough sunshine, NE NJ could warm up into the mid 90s. With dew points in the lower 70s, humid conditions are expected tomorrow, and the heat index may reach the upper 90s. Due to a south wind, temperatures in Long Island/S CT will stay cooler, in the lower to mid 80s across most of the area. Upper 70s are expected near the coastal areas, with upper 80s towards western Long Island/SW CT.

Weekend And Next Week:

- Warmth will continue from Friday and beyond. Little change is expected in the conditions, as temperatures stay in the upper 80s to mid 90s from NYC and further west and in the mid to upper 80s in Long Island/S CT with partly sunny skies from Saturday through next Wednesday/Thursday, when the next cold front should reach the region, bringing a risk of thunderstorms late next week along with slightly cooler temperatures.

Wednesday, July 27, 2011

As a slightly cooler air mass moved into the region, today brought slightly cooler temperatures, peaking in the mid 80s inland, mid to upper 80s in the immediate NYC area, and in the lower to mid 80s in Long Island and southern Connecticut. These temperatures are near the average for this time of the year, but as a warmer air mass moves in, will be the coolest temperatures until the middle of next week as another heat wave affects the area starting tommorrow.

Tomorrow and Friday: Warm, Humid, Stormy

A warmer air mass will start to move into the area tomorrow. As a result, temperatures will warm up, reaching the mid to upper 80s inland, upper 80s to lower 90s in the immediate NYC area, and mostly in the mid 80s further east due to a south wind.

There is the potential for a MCS (Mesoscale Convective System) to move into the area tomorrow night. Forecasting MCS type events can be very difficult, but the potential is there for one to affect the region, and if one does reach the area, it would be capable of bringing heavy rain and gusty winds. More information on this will be posted tomorrow.

Afterwards, Friday will bring warmer temperatures along with more humidity, with temperatures reaching the upper 80s to lower 90s from NYC and further west, with the heat index reaching the upper 90s. The potential is there for strong thunderstorms to affect the area in the evening and overnight hours. Stay tuned for more information on the potential strong storms for Friday.

Weekend - Next Week: Warmth Continues

The storms on Friday night will fail to end the warmth. Temperatures on Saturday will only get warmer, reaching the lower to potentially mid 90s from NYC and further west. The main improvement from Friday is that the humidity will be lower. Temperatures will slightly cool down on Sunday but will remain warm.

There is some slight uncertainty for early next week, as some models suggest that a strong back door cold front moves through and drops temperatures into the mid 80s. At this time, I'm thinking that some models may be showing the back door cold front a little too strong, and I expect temperatures to cool down into the mid to upper 80s in the immediate NYC area and mid 80s across the rest of the area. By mid-late next week, another cold front approaches the region, which will likely bring slightly warmer temperatures again ahead of another potential risk of thunderstorms. More information will be posted on the longer range as details become clearer.

Tuesday, July 26, 2011

- The 5-Day Forecast page was not updated, but the forecast has not changed since yesterday and is still valid.

- The Tropics page is still updated daily, twice a day, unless there is an active tropical cyclone approaching the US, when updates will be posted more frequently. The current activity graphic on the right side of the blog is updated twice a day as well. Tonight's update now has a 60% risk of development for Invest 90L, which will move into the Gulf of Mexico tomorrow.

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Weather Summary:- With a slightly cooler air mass moving in, tomorrow will slightly cool down, with most of the area in the mid to upper 80s for highs. Thursday will warm up with temperatures in the mid 80s to lower 90s across the area, with the warmest temperatures in the immediate NYC area where widespread lower 90s are expected.

- Friday will be hotter, with temperatures in the lower to mid 90s from NYC and further west and mid 80s to lower 90s east of NYC. Along with dew points in the lower 70s, the heat index values will likely reach 100 degrees, and a heat advisory will likely be issued tomorrow morning for Friday. Regarding the storm potential, the latest models are showing almost no precipitation on Friday, but with the given set up, I kept a risk of potentially strong storms in the forecast for Friday.

- Friday will start a heat wave which will last through early-mid next week. Temperatures through the weekend will stay in the upper 80s to mid 90s from NYC and further west, and the mid to upper 80s east of NYC. Temperatures are likely to slightly warm up around early next week ahead of a potential cold front by early-mid next week.

8:45 PM: The storm in New York City has intensified, and is currently a strong thunderstorm covering NW Brooklyn and Queens. This storm will produce heavy rain and gusty winds as it continues to move ESE, affecting the rest of Brooklyn and Queens, later on reaching Long Beach and southern Nassau county.

8:25 PM: The storms in southeastern New York earlier this afternoon ended up going through northern Westchester county into SW Connecticut. While these storms are no longer present, there are four storms cells over northern New Jersey, all of them moving towards the same direction in a line, targeting the same area from Sussex to West Passaic to northern Bergen with heavy rain and thunderstorms over the next 1-2 hours. These storms are not severe, but there is a strong cell near Franklin, NJ, which is expected to follow the path of the other storms as well. There is also an area of heavy rain near Patterson which will move ESE, towards Manhattan, within the next 1/2 hour.

Most of the area is dry, but there are some more storms in SW Connecticut. There are two small yet heavy thunderstorms near Danbury, CT, and there is a large heavy cell just north of Bridgeport, CT, moving ESE and offshore into the Long Island Sound.

3:30 PM: Yesterday's update mentioned the potential for isolated activity today north of NYC, with most of the storms staying well north of NYC. With a low pressure moving through northern New York, widespread strong to severe thunderstorms have developed this afternoon in New York and are moving southeast, with a particular area of severe storms in east central New York intensifying as it is moving towards western Massachusetts/NW Connecticut. Meanwhile, a few strong thunderstorms in formed northeastern Pennsylvania, which are currently moving towards the western half of the area.

Most of the activity is to the north of the area, but two storms are approaching the northwestern parts of the area. The first storm is approaching Monticello, NY, which will move into NW Orange county in the next 3/4 hour, producing heavy rainfall and gusty winds. The second storm is near Scranton, PA, and is moving towards Sussex county, NJ. This storm is weaker than the storms further north, and is expected to begin weakening by the time that it reaches Sussex county.

The parameters in the area are supportive of severe weather, with decent lift index/CAPE values. The best lapse rates, however, are to the north of the area, and there is nothing to spark widespread storm development in the area. As a result, the best risk of strong thunderstorms this afternoon will be in interior SE NY, focusing over Orange/Rockland/Putnam counties in NY. The rest of the area can expect to see partly to mostly cloudy skies with dry conditions. If necessary, storm updates will be posted, otherwise the next update will be posted tonight.

Monday, July 25, 2011

Since the last update this afternoon, the squall line in northeastern Pennsylvania weakened and eventually collapsed before reaching the immediate NYC area as it moved into a stable air mass. This ended tonight's activity, and dry conditions will continue through the overnight hours except for some isolated showers before midnight.

Behind today's storms, warmer temperatures will return into the area, with 90s making an appearance in parts of the immediate NYC area tomorrow. Temperatures are mostly expected to stay in the upper 80s to lower 90s from tomorrow through next weekend, but as a brief surge of heat reaches the region on Friday, hotter temperatures with more humidity are expected, along with a risk of strong to potentially severe thunderstorms.

Tomorrow's Outlook:

With tonight's cold front clearing the area, tomorrow will bring partly cloudy skies with a west wind. High temperatures will be warmer than those of today, reaching the upper 80s inland, upper 80s to lower 90s in the immediate NYC area, and the mid to upper 80s in Long Island and southern Connecticut. An isolated shower or thunderstorm cannot be ruled out in the late afternoon/evening hours north of NYC, but most of tomorrow's storms will stay well to the north of the area.

Wednesday - Thursday: Warmth Continues

Wednesday and Thursday are both expected to bring similar conditions. The main difference is that Wednesday will be slightly cooler with a NW wind, and Thursday will bring more cloud cover with a south wind. High temperatures on Wednesday will be in the mid 80s inland, mid to upper 80s in the immediate NYC area, and in the mid 80s in Long Island/S CT. Thursday will be warmer from NYC and further west, with temperatures reaching the upper 80s to lower 90s, but mid 80s are expected again in Long Island/S CT, with colder temperatures near the southern coastal areas.

Friday And Weekend: Stormy, Then Dry And Warm

A brief surge of heat will reach the region on Friday, and the area is expected to be in the northern edge of this surge of heat. The intensity of the heat won't be as strong as what we saw at the end of last week, but will still be enough to bring temperatures from NYC and further west into the lower to mid 90s. Humid conditions are expected as well, which could bring the heat index to the upper 90s-100 degrees. With the area near the northern end of the heat, thunderstorms are likely to affect the northern Mid Atlantic, including the area, and the southern Northeast. Modeled parameters are supportive, and the potential is there for strong to potentially severe thunderstorms on Friday. Stay tuned for more information on Friday's potential storms.

After Friday, the storms will exit the area, but the warmth will stick around. Temperatures are expected to be in the mid 80s to lower 90s across the area next weekend. Beyond next weekend, there is more uncertainty given the time range, but at this time, it appears that we may see temperatures warm up early next week ahead of another cold front. More information will be posted on the longer range as details become clearer.

Below, storm updates will be posted on the heavy rain and thunderstorms that will affect parts of the area through this evening.

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6:20 PM: Light to moderate rain continued to affect northern NJ, SE NY and NYC over the last two and a half hours, with light rain affecting western Long Island. The rain is currently weakening, with occasional light rain expected by 6:30 PM. Meanwhile, a line of strong thunderstorms in Pennsylvania is moving towards the area. The line is breaking up with the strong storms staying further south, moving towards SE PA and central New Jersey, but there is a strong thunderstorm near NE PA with an organized structure, potentially containing strong wind gusts. This storm is moving SE, and over the next 1/2 hour will move through the northern half of Sussex county. This storm is starting to weaken as well, but will be capable of producing heavy rainfall and gusty winds.

3:30 PM: Moderate rain and thunder continues to affect NW NJ, while the rain is weakening as it is moving into NE NJ and NYC. Light to occasionally moderate rain is now starting in NYC/NE NJ, and will continue over the next few hours. Further east, very light rain is moving into SW CT and far western Long Island, where most of the rain will stay light.

2:30 PM: Since the last update, widespread strong to severe thunderstorms have formed across central Pennsylvania and started to move east. The intense storms have failed to move east of a certain point in east-central PA, which is where the warm front is currently stuck, and instead these storms are spreading out and weakening into larger areas of moderate to heavy rain and thunder. All of NW NJ is currently covered by moderate rain and thunder, and this area of rain will reach the rest of NE NJ and NYC within the next 1/2 to 1 hour. As the rain moves into NYC, it is expected to begin weakening, and Long Island will see lighter rain amounts from the same area of rain.

Yesterday, a cold front moved through the area, bringing scattered thunderstorms especially in northern New Jersey. This cold front brought an end to the heat wave which has brought record temperatures into the region, and the front is now to the south of the area, which will help keep temperatures below the 90 degree mark today. A weak low pressure will move towards the Northeast, bringing another cold front through with thunderstorms affecting the region, but the NYC area will likely be spared from the majority of the action today.

Today's Set Up: The cold front is stuck to the south of the area as of this morning, and the warm front associated with the low pressure is currently near central Pennsylvania. The front will continue to move east for now, but there is a high pressure off the coast which will make it more difficult for the warm front to move east as it reaches the area. As a result, it is expected to remain near or just west of NYC through this evening, keeping an onshore SE wind in the area resulting in a stable air mass, while places further west become more unstable. Later tonight, the warm front is expected to move through, but it will be quickly followed by the cold front, keeping the area under a stable air mass.

We have seen this type of scenario happen several times throughout the spring. Not all cases were the same, but in most of them, we ended up seeing storms further west, towards Pennsylvania, weakening and later dissipating as they moved through NJ towards NYC. This is the same scenario that most of the models are showing for today as well, with most of the thunderstorms staying in Pennsylvania, and some models fail to bring any rain to NYC. This does not mean that the area will not see any rain, but the stable air mass will cause any storm that enters the area to begin weakening as it approaches NYC.

Today's Outlook: Instability further west today will cause strong to locally severe thunderstorms to form to our west, towards central Pennsylvania, New York and Virginia. These storms will then move east towards the more stable air mass over the area. Some storms are expected to move into northern NJ this afternoon evening, but as they do so, they will lose their severe characteristics. Despite this, they will still be capable of producing heavy rainfall in northern NJ and interior SE NY. As these storms continue to move towards the coast, they should rapidly collapse by the time that they reach and pass NYC. As a result, the best risk of storms today is to the west of NYC, where locally heavy rainfall is possible, and Long Island/southern Connecticut are expected to stay mainly dry other than some isolated shower/thunderstorm activity tonight. Storm updates will be posted this afternoon and evening if necessary.

Sunday, July 24, 2011

Below, brief updates will be posted on the current storms affecting the NYC area.

**Click on the images to the left of each update to view them in a larger size.**

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2:45 PM: As the cold front is moving through the region, heavy but non-severe thunderstorms are affecting portions of the area. The main storm is currently near northern Warren county and is moving SE, producing heavy rainfall, gusty winds and potentially small hail. Another heavy thunderstorm is in central Westchester county and is moving towards the SE, but this storm is weakening, and will affect eastern Nassau/western Suffulk counties within the next 1/2 to 1 hour with light rain and thunder.

Otherwise, there are a few other heavy thunderstorms in northern New Jersey moving SE as well, especially in Sussex and West Passaic. The storm in Sussex has a narrow band of light to moderate rain stretching eastwards towards western Bergen county, and is moving SE along with the storm. This will result in at least some rain across most of northern New Jersey.

Saturday, July 23, 2011

With the large ridge still covering the region, today was another hot day across the area. Widespread cloud cover, however, prevented temperatures from getting as hot as yesterday, with highs today reaching the lower to mid 90s inland, mid 90s to lower 100s in the immediate NYC area, lower to mid 90s in southern Connecticut, and the lower to upper 90s in Long Island. Newark, which hit 108 degrees yesterday, reached a maximum temperature of 102 degrees today.

A cold front currently well to the west of the area is slowly approaching, and will move through the area tomorrow. Today, this front only produced isolated activity across the region, and this front will be mostly dry when it passes through tomorrow. As a weak low pressure enters the region, Monday is likely to bring more widespread showers and thunderstorms along with much cooler temperatures. This cool down will be brief, however, as temperatures warm up into the 90s once again by late next week.

Tomorrow's Outlook:

Tomorrow will bring much cooler temperatures with less humidity into the area. As the cold front moves through, partly cloudy skies are expected with a risk of isolated showers and thunderstorms, and while any storm that forms could become strong, storms will stay isolated once again, and a good part of the area is likely to be dry. Places from NYC and further west will reach the upper 80s to lower 90s, and with a west/WNW wind, Long Island and southern Connecticut will reach the mid to upper 80s.

Monday - Tuesday: Weak Low Pressure Brings Rain

A weak low pressure is expected to move into the northern Northeast between Monday and Tuesday. This will bring widespread rainfall into the region on Monday followed by a cooler air mass for Tuesday. Monday's strong thunderstorm risk at this time is not very impressive with severe weather parameters not very supportive of severe weather. Locally heavy rainfall is possible, but widespread heavy rainfall amounts are not expected at this time. More information will be posted tomorrow on Monday's rain risk.

Along with the storm, cooler temperatures are expected. A southeast wind will bring much colder temperatures into the area, only peaking in the lower to mid 80s from NYC and further west, and the upper 70s to lower 80s east of NYC. As the storm exits on Tuesday, partly sunny skies are expected with warmer temperatures, reaching the mid 80s across most of the area.

Wednesday And Beyond: Heat Returns

The break from the heat won't last for long. Tuesday's low pressure will briefly keep cooler temperatures over the Northeast for Wednesday, when temperatures will peak in the mid to upper 80s across most of the area with parts of NE NJ potentially reaching 90 degrees in the warmer case scenario, but a much warmer air mass in the central US will spread east towards the region once again, with the ridge shifting east once again, bringing the focus of the heat closer to the area. The intensity of the heat should be weaker than the current heat wave, and appears to be shorter lasting as well, but temperatures should get hot once again, potentially surging well into the 90s on Friday and/or Saturday before cooler temperatures return. More information will be posted over the next several days on next week's heat.

**Due to some difficulties with the internet connection earlier today, no updates were posted in the morning/early afternoon hours. I am currently working on updating most of the website, and the following will be posted or updated this evening:

- A detailed summary of last week's observations and forecast verification- Tonight's post, which will discuss Monday's potential storms and the next surge of heat for late next week- Updated Tropics and Weather Alerts pages

Friday, July 22, 2011

- The 5-Day Forecast page was updated for the short term, through Sunday, though the forecast beyond Sunday was discussed below. The 5-Day Forecast page will be updated tomorrow morning through Wednesday.

- Two updates will be posted tomorrow morning; one will be a brief update about tomorrow's heat and the risk of isolated thunderstorms, and the other will be a summary of this week and forecast verification.

- A new "Tropics" page was created. Updates will be posted in this page starting tomorrow morning.

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Heat Summary:

Across the area, today was one of the hottest days ever recorded in the New York City area, and across parts of the area and the region, even broke all time heat records. Newark, NJ reached an all time record high of 108 degrees, which produced a heat index well into the 110s when combined with dew points in the upper 60s to lower 70s. In addition to Newark's record, Bridgeport in Connecticut tied their all time record high of 103 degrees. Central Park's 104 degree high temperature is their 2nd warmest temperature on record, and Teterboro's 104 degrees is two degrees below the all time high temperature of 106 degrees. Below are the high temperatures today across the area, from the National Weather Service:

Even though the temperatures were already hot enough, the humidity made the heat even worse. When Newark reached 108 degrees, the humidity resulted in a heat index of 117 degrees. Heat indices in the 110s were observed across most of the immediate NYC area due to dew points in the 70s combined with very hot temperatures. During July 2010, the area also observed a heat wave early in the month with similar temperatures, but during that heat wave, the humidity was not as significant as it was with this heat wave. The heat index values observed with this current heat wave are abnormally high and are quite rare for the NYC area.

Today brought the worst of this heat wave. Tomorrow, unfortunately, won't bring any significant improvements as the heat and humidity continue with the only difference being slightly lower temperatures and humidity. Sunday will bring relief in the form of a cold front, which will be followed by much cooler temperatures on Monday along with the risk of thunderstorms. This cool down is only brief, however, as another heat wave is possible once again late next week.

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Tonight's Outlook:

Temperatures are still very warm across most of the area, and as of 9 PM, temperatures were in the mid 80s inland, lower to upper 90s in the immediate NYC area, and in the upper 80s to lower 90s east of NYC. Temperatures will continue to gradually drop overnight, reaching the mid 70s inland, upper 70s to mid 80s in the immediate NYC area, and the mid 70s to lower 80s in Long Island and southern Connecticut. With the humidity still in place, the heat index value will stay high, dropping into the upper 80s at the lowest in NYC/Newark. There is the potential that if low temperatures end up in the mid to upper 80s in NYC/Newark, these locations could break the record for the highest minimum temperature.

Tomorrow's Outlook: Heat Continues

Tomorrow will bring only minor improvements as the heat and humidity continue across the area. Temperatures at 850 mb, which were near 24 degrees celsius today, will slightly lower tomorrow to around 22 degrees celsius. As a result, high temperatures will be slightly lower as well, reaching the mid to upper 90s inland, lower to mid 100s across most of the immediate NYC area with a west wind. With a WSW wind in Long Island/southern CT, however, temperatures will be lower than those of today, reaching the mid 90s in southern Connecticut and the mid to upper 90s in Long Island, except for the immediate southern coast which should stay in the lower 90s.

Dew points will be slightly lower as well, reaching the upper 60s to lower 70s across the area. This will result in slightly lower but still dangerous heat index values across the area, which are expected to end up near 100 degrees inland, 105 degrees in the immediate NYC area, and 95-100 degrees in Long Island/southern Connecticut.

Partly sunny skies are expected tomorrow, but as the cold front approaches, thunderstorms may be possible tomorrow afternoon. At this time, the NAM model is the most bullish with this storm risk, showing widespread precipitation tomorrow afternoon which prevents temperatures from getting into the 100s in the area. The rest of the models, however, are drier, and the parallel NAM run is much drier as well. At this time, I put a risk of isolated thunderstorms in the forecast, and any storms that form could become strong with the instability in place, but widespread activity is not expected, and most places are expected to stay dry at this time. Another update will be posted tomorrow morning, which will discuss any storm risk tomorrow.

Sunday - Monday: Relief From Heat

A cold front will move through on Sunday, bringing needed relief from the heat. Temperatures will still be hot, reaching the upper 80s to lower 90s across the area with a few mid 90s possible in NE NJ, but the humidity will be much lower, with dew points dropping into the lower to mid 60s across the area, which will keep the heat index below 95 degrees. In addition to the cooler temperatures, scattered thunderstorms are possible, but are not expected to be widespread at this time.

Monday, however, will bring much cooler temperatures. A low pressure to the north of the area will move east, bringing a SE wind into the area. Meanwhile, mostly cloudy skies are expected along with widespread showers and thunderstorms. This will bring a much more significant cool down into the area, with temperatures only reaching the lower to mid 80s from NYC and further west, and the upper 70s to lower 80s in Long Island and southern Connecticut.

Tuesday And Beyond: Heating Up Again

As the low pressure moves out by Tuesday, warmer temperatures will begin to return. The low pressure will likely keep a weak trough around the NE around Tuesday/Wednesday, which will bring a WNW wind into the area along with temperatures in the lower to mid 80s across most of the area and a few upper 80s in the immediate NYC area. By late next week into next weekend, there is some uncertainty with the exact scenario, but it appears that the ridge briefly shifts east again closer to the area, allowing another strong surge of heat to potentially affect the region. Should this scenario verify, the heat is likely to be weaker and shorter lasting than what we are current seeing, but the potential is there for temperatures to surge well into the 90s once again for a day or two in the area, with a few 100s possible across parts of the Northeast/Mid Atlantic once again. Stay tuned for more information on the longer range with a brief update tomorrow morning.

3:00 PM, July 22, 2011:***As of 2:51 PM on Friday, July 22, 2011, Newark in New Jersey reached an all time record high temperature of 108 degrees. The previous all time record was 105 degrees, recorded on August 9, 2001.***

The rest of the area is recording very hot temperatures as well, with 103 degrees in Teterboro and Central Park, and 101 degrees at the JFK airport. Temperatures will continue to rise over the next 1-2 hours before becoming steady and starting to gradually drop, and other locations may tie or break their all time records as well. Heat indices will remain at dangerously high levels, in the 110 to 120 degree range. Stay tuned for more updates on the heat over the next several hours.

The blog will be updated today. Stay tuned for several updates later this afternoon with two posts, one discussing the excessive heat and tropical activity with the other reflecting on what the area saw this week, and an updated 5-Day Forecast.

Sunday, July 17, 2011

Note: This blog is going on a weather related trip over the next week. The next update, along with some comments on the trip, will be posted on Saturday, July 23.

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A massive ridge is currently centered over the central United States, bringing extreme heat to that region. Some of the heat from this ridge is spreading towards the region, which is bringing temperatures into the 90s. Meanwhile, a storm in Canada will bring a cold front through tomorrow, bringing a risk of severe weather. Behind this front, temperatures will slightly cool down, but by late next week, temperatures will warm up even more, potentially reaching the 100 degree mark in parts of the area.

Today's Outlook:

The outlook for today has not changed since yesterday. Mostly to partly sunny skies are still expected, with highs in the upper 80s to lower 90s from NYC and further west, and the mid 80s across most of Long Island and southern Connecticut.

Monday: Severe Storms Possible

A cold front will move through the region on Monday, bringing a risk of strong to severe thunderstorms. Unlike most of the outbreaks we've seen in the region this summer, however, this set up is more favorable for severe weather. In addition to supportive lift index and CAPE values, bulk shear is also modeled to be supportive, between 35 and 45 knots. We had some cases where there was favorable bulk shear this summer which did not end up over the areas which saw severe weather, but in this case, the supportive area of bulk shear is expected to end up over the same region expected to see thunderstorms, which is already a sign of a better chance of severe thunderstorms. Lapse rates are expected to be supportive as well.

With the factors above in place, there is at least a 15% risk of severe weather across most of the area. The best risk of severe thunderstorms is expected to end up in southern New England and parts of southern New York State, which includes the northern parts of the area. These places have the most supportive parameters, and at this time, I placed a low-end 30% risk in those areas. Thunderstorms across the area will be capable of producing gusty winds, heavy rainfall, and small hail.

Medium Range Heat Wave: 100s Possible

Behind this cold front, temperatures will only slightly cool down. Tomorrow will bring lower to mid 90s from NYC and further west, and Tuesday will bring upper 80s to lower 90s from NYC and further west. Mid to upper 80s are expected as well in Long Island and southern Connecticut. Wednesday will bring similar temperatures to those of Tuesday.

Things will change by Thursday, however. The large ridge currently over the central US will shift eastwards, so that the focus of the heat will be further east as well, closer to the area than we've seen most of this summer. A strong cold air mass in SE Canada will attempt to drop southeast towards the region, but at least early in this time frame, will only make it as far south as northern New England, allowing the excessive heat to spread into the NYC area.

Forecast for the Tri-State Area: Temperatures on Thursday will begin to warm up, reaching the lower to potentially mid 90s inland, mid 90s across most of the immediate NYC area, and with a southwest wind, Long Island and southern Connecticut should reach the mid 80s to lower 90s. Humidity will begin to slightly increase as well, allowing the heat index to reach the upper 90s in the immediate NYC area.

Friday is likely to be the hottest day of this heat wave, though Saturday could bring similar conditions as well. 850 mb temperatures are modeled to be in the 21-24c range, similar to what we saw with the July 2010 heat wave. Mainly dry conditions are expected along with mostly/partly sunny skies and a WSW wind. Unless there is a significant change with the expected set up, the conditions above are capable of bringing the hottest day of the year across the area. High temperatures are likely to reach the mid to upper 90s inland, upper 90s to potentially lower 100s across most of the immediate NYC area, and Long Island/southern Connecticut are likely to end up in the upper 80s to mid 90s, though upper 90s could be possible closer to NYC in the warmest case scenario. Humidity is expected as well, with dew points modeled to be near the upper 60s to lower 70s. This would bring the heat index into the mid-upper 100s in the immediate NYC area.

Forecast Uncertainty: The forecast for Friday is not 100% certain yet, but based on the set up for this time frame and the agreement between the models and model ensembles regarding the intensity and placement of the heat, there is a relatively high probability that Friday ends up bringing conditions similar to those mentioned above. There is the possibility that the heat ends up being slightly weaker than expected or that the back door cold front drops south of the expectation, which would result in cooler temperatures than the above, but even in these scenarios, Friday is likely to end up as a hot and humid day.

Beyond Friday, there is increasing uncertainty regarding another cold front, as the GFS has the heat lasting through early next week, the ECMWF brings a weak back door cold front through which slightly cools down temperatures, and the GGEM brings a stronger cold front through with temperatures returning into the 80s. At this time, I am siding with a scenario closer to that of the ECMWF, where temperatures cool down into at least the upper 80s to mid 90s on Saturday or Sunday, followed by another warm up by early next week. There is more uncertainty, however, and the confidence level in the forecast decreases beyond Saturday. With the next update, either late on Friday or on Saturday morning, I will discuss what the forecast is from that point and beyond.

Saturday, July 16, 2011

Note: The 5-Day Forecast page was updated tonight. An update discussing Monday's storms and the long range heat will be posted tomorrow morning.

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With the high pressure previously over the region sliding offshore, a much warmer air mass is spreading into the region, with temperatures warming up as well, reaching the upper 80s inland, upper 80s to lower 90s in the immediate NYC area, and the lower to mid 80s in Long Island and southern Connecticut. Today ended up slightly warmer than expected in the immediate NYC area, though the forecast for Long Island and southern Connecticut verified.

As a warmer air mass continues to spread into the region, temperatures will continue to warm up, reaching the lower 90s over a more widespread area tomorrow. A cold front will move through on Monday, bringing a risk of strong thunderstorms along with increased heat and humidity, with temperatures reaching the mid 90s in parts of the immediate NYC area. Temperatures will slightly cool down on Tuesday/Wednesday, but by the late week, a massive ridge in the central US will spread towards the region, bringing the potential for the hottest temperatures of the year.

Tomorrow's Outlook:Warmth will continue to spread into the region tomorrow, with the result being slightly warmer temperatures than those of today. A southwest wind is expected along with partly sunny skies, which will result in temperatures reaching the upper 80s to lower 90s from NYC and further west. Widespread mid 80s are expected in Long Island and southern Connecticut, with lower 80s near the immediate coast and upper 80s closer to NYC.

Monday - Wednesday: Stormy, Then Slightly CoolerAs a cold front approaches the area on Monday, the heat and humidity will only get worse, with temperatures reaching the lower to mid 90s from NYC and further west, though temperatures will be cooler further east, reaching the mid to upper 80s across most of Long Island and southern Connecticut. Combined with dew points near 70 degrees, the heat index may reach the upper 90s in parts of the immediate NYC area.

Along with the cold front comes a risk of thunderstorms. At this time, it appears that this front may bring a better risk of rainfall than most of the previous fronts we've seen so far this month, and the parameters on the models are supportive of at least some severe weather, though the best risk of severe thunderstorms will likely stay to the north of the area. Precipitation amounts are more uncertain, and while locally heavy rainfall amounts are possible, widespread heavy rainfall amounts are not expected. The latest operational NAM runs are showing a widespread 1-2 inch area, but is a wet outlier, compared to the other models and the parallel NAM runs as well. More information on Monday's storms will be posted with an update tomorrow morning.

By Tuesday and Wednesday, a slightly cooler air mass will move in as a high pressure moves into the region. Temperatures will not significantly cool down, but at least upper 80s to lower 90s are expected across the area on Tuesday. Wednesday will bring upper 80s to lower 90s from NYC and further west, but slightly cooler temperatures further east, reaching the mid to upper 80s across most of Long Island/southern Connecticut except for the immediate coast.

Friday, July 15, 2011

Note: The 5-Day Forecast was updated this morning. Another discussion, focusing on Monday's severe weather risk and the late week potential heat wave, will be posted tonight.

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With a high pressure over the region, yesterday brought mostly to partly sunny skies across the area with highs reaching the lower 80s inland, lower to mid 80s in the immediate NYC area, and the upper 70s to lower 80s across Long Island and southern Connecticut. Today will bring similar conditions as the high pressure stays over the region, but as the high pressure moves offshore, heat and humidity will return by Sunday. A cold front along with thunderstorms will bring a relief from the heat on Tuesday and Wednesday, but the potential is there for a major heat wave late next week that may challenge the June 6-8 heat wave for the hottest temperatures of the year.

Today's Outlook:

Today will bring similar conditions to those of yesterday as a high pressure remains over the region. Mostly sunny skies are expected along with a light and variable wind. High temperatures will reach the lower to potentially mid 80s inland, mid 80s in the immediate NYC area, and the lower 80s across Long Island and southern Connecticut. Slightly cooler temperatures are expected along the immediate coast.

Weekend Outlook:

With the high pressure sliding offshore, winds will turn more towards the SSW/southwest during the weekend, allowing the warmth to slowly build in. A massive ridge is currently centered over the central United States, with widespread 500 mb heights over 594 dm expected, a clear signal for extreme heat. As we have seen most of this summer, the ridge has focused over the central US while a short lasting surge of heat spreads into the region, and at least for this weekend, this will be the case once again.

Warmer 850 mb temperatures will spread into the region, which will allow surface temperatures to warm up as well, reaching the mid to upper 80s from NYC and further west on Saturday and lower to mid 80s further east. Sunday will bring even warmer temperatures, with more widespread upper 80s from NYC and further west, and a few lower 90s are expected in the immediate NYC area, especially in NE NJ.

Monday - Wednesday: Cold Front Moves Through, Severe Storms?

So far this summer, the area has been mostly spared from major widespread severe weather outbreaks. We are not looking at a widespread major severe weather outbreak for Monday, but the risk of thunderstorms is higher than what we have recently seen. A cold front will approach the area on Monday, bringing warmer temperatures, reaching the lower to mid 90s in the immediate NYC area, but along with the heat comes a risk of severe thunderstorms. The latest models are showing high precipitable water values, decent LI/CAPE values, and supportive lapse rates as well, factors which are all supportive of severe weather. The best risk of severe weather should be in the Northeast, to the north of the area, but some thunderstorms are expected in the area as well, and the latest modeled parameters support at least a low risk of severe weather in the area. Stay tuned for more information on Monday's severe weather risk.

The intensity of the cold front is the main question at this time. The ECMWF once again fails to bring any significant cool down with the front, while the GGEM brings a significant cool down for the middle of next week. Both solutions are likely extremes, and the most reasonable and least extreme solution at this time is the GFS, which shows a slight cool down for the middle of next week with temperatures cooling down into the mid to upper 80s across most of the area for Tuesday and Wednesday. At this time, I went along with a solution close to that of the GFS, with widespread mid to upper 80s behind the cold front on Tuesday, and a few lower 90s cannot be ruled out. Wednesday will bring slightly cooler temperatures.

Thursday And Beyond: Big Heat Possible

As previously mentioned, the center of the ridge for now will focus over the central US. It is possible, however, that this changes by late next week. Behind Wednesday's brief cool down, there is a general model consensus for the center of the ridge to shift east, taking it closer to the area, and allowing more heat to make it into the region. Each model handles this differently, with some of them showing the possibility that a back door cold front drops through the Northeast during the peak of the heat, but should the heat spread in with no back door cold front, this has the potential to match, if not pass the hottest temperatures of the June 6-8 heat wave, when Teterboro in Bergen county (NE New Jersey) reached 100 degrees. The ECMWF is the hottest model, showing 850 mb temperatures which support high temperatures easily reaching the 100s, but was not used for today's update especially when considering that it tends to have a warm bias with heat waves and is currently the most extreme solution.

This is still in the medium range and is subject to change, but at this time, given the potential set up during this time frame, temperatures are likely to significantly warm up around Thursday/Friday, and if no back door cold front comes through, the heat should last through next weekend. Temperatures may be capable of surging well into the 90s with this type of set up, and parts of the region may even reach the 100s. Stay tuned for more information on the potential heat wave with tonight's update.

Wednesday, July 13, 2011

The forecast for today originally called for mostly sunny skies and high temperatures in the mid 80s to lower 90s. Unlike the expectation, however, scattered thunderstorms formed and affected parts of the area, especially northern New Jersey, NYC, and parts of Long Island, bringing gusty winds and locally heavy rainfall. High temperatures were slightly cooler than expected as a result, peaking in the mid 80s inland and in the mid to upper 80s in the immediate NYC area, Long Island, and southern Connecticut. While this round of rain was unexpected, it is certain that there will be no rain tomorrow and on Friday as a high pressure moves over the area.

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As mentioned above, today brought unexpected storms into the area with cooler temperatures than expected. Tomorrow through the weekend will be dry, however, as a high pressure moves over the area, which will prevent rain from affecting the area and keep mainly sunny skies in place. This high pressure will bring seasonable temperatures as well, peaking in the upper 70s to mid 80s across the area.

With the high pressure exiting the region by Sunday, more cloud cover will return, and as the wind begins to shift more towards the south/SW, hotter temperatures will return, with 90s returning into the immediate NYC area for Monday and Tuesday before the next cold front comes through. Unlike the more recent cases, however, it is possible that the cold front may have less of an influence than previous scenarios we've seen, and if this scenario verifies, excessive heat may affect the area by late next week.

Thursday - Saturday: High Pressure In Control

With the cold front out of the area and a high pressure moving in, tomorrow will bring sunny skies to the area with a NNE wind expected. Seasonably mild high temperatures are expected as well, with high temperatures peaking in the lower to mid 80s from NYC and further west, and in the upper 70s to lower 80s across Long Island and southern Connecticut.

With the high pressure still in control, similar conditions will continue across the area on Friday. By Saturday, the high pressure will drift offshore, which will bring more of a SSW wind into the area. This will allow warmer temperatures to slowly return into the area, reaching the upper 80s in parts of the immediate NYC area. With the expectation for next week, however, these upper 80s may end up being some of the coolest temperatures the area sees until the last week of July.

Sunday And Monday: Heat Slowly Returns

A massive ridge will develop in the central United States during the weekend into early next week, with a widespread area of 500 mb heights above 594 dm, which indicates extreme heat with the potential for record temperatures once again in that region. Some of that heat will spread into the region as well by Sunday/Monday, with 850 mb temperatures warming up into the 16-18 degree celsius range.

As a result, Sunday will still bring mostly sunny skies to the area with highs in the mid to upper 80s from NYC and further west, with a few lower 90s possible in NE NJ, along with cooler temperatures in Long Island/southern Connecticut due to an onshore wind. Monday will bring more widespread warmth, with upper 80s to lower 90s from NYC and further west with mid to potentially upper 80s in Long Island/S CT, and a few places may get close to the 95 degree mark in the warmer case scenario.

Tuesday And Beyond: Excessive Heat?

Model/Scenario Analysis: A cold front will approach the region on Tuesday, but what this cold front does will determine the set up for the remainder of next week into next weekend. The front will be associated with a low pressure well to the north of the US/Canada border, and some models show the front failing to bring any cool down. In fact, the ECMWF model intensifies the heat, with both its early morning and afternoon runs showing potentially record heat in the region, with 850 mb temperatures in the 22-26c range, indicating temperatures reaching the 100s. The ECMWF is most likely exaggerating the heat intensity for next week, but it is possible that the front fails to bring any cool down into the area.

Meanwhile, the other models are showing more of an influence from the cold front, but the exact scenario varies with each model. The GGEM and DGEX are the likely outliers, with the DGEX developing a strong low pressure near Maine which brings a stronger cool down for a longer period of time, with the GGEM developing a coastal low, a highly unlikely solution. Both models, however, ultimately end up showing a building ridge at the end of their runs. The GFS is still showing different solutions from run to run, as should be expected in the longer range, but at this time the overall idea it has is a more reasonable one, where heat spreads into the region for Monday and Tuesday, followed by a brief and weak cool down on Wednesday. The excessive heat then builds in again from Thursday to around Saturday.

This is still in the longer range and the smaller details are easily subject to change, but when looking at the overall set up, the main factor that drives this heat wave is the center of the ridge which is modeled to shift further east, from the central US more towards the eastern US, which has not happened with most of the heat spells we've seen so far this summer. The ensemble means also show big heat spreading into the region, with the GFS ensemble mean showing decent agreement for hot temperatures late next week. While there is still time for changes in the expectations, at this time I am expecting hot temperatures for Monday and Tuesday, a brief cool down around Wednesday which may potentially last through Thursday at the latest, followed by a building ridge with excessive heat late next week into next weekend.

Forecast for the NYC area: Monday and Tuesday are expected to be hot days in the area, with lower to mid 90s in the immediate NYC area on Tuesday. A cold front will affect the region, bringing a risk of thunderstorms on Tuesday, but it is still too far in the future to determine how high the risk of rain actually is. As previously mentioned, I am expecting a brief cool down around Wednesday with temperatures cooling down slightly below the 90 degree mark, but temperatures should warm up late next week, reaching well into the 90s. More information will be posted on this over the next several days, including any potential changes in the forecast scenario.

Tuesday, July 12, 2011

As a cold front started to move through the region, today brought some of the hottest temperatures of this summer so far, with temperatures reaching the lower 90s inland, mid to upper 90s across most of the immediate NYC area, and the upper 80s to mid 90s across most of Long Island and southern Connecticut. In fact, some high temperature records were broken today, such as Newark where the official high was 99 degrees.

While the humidity will be much lower tomorrow, the temperatures will not cool down as quickly, with some lower 90s expected in the immediate NYC area and parts of Long Island tomorrow. By Thursday, however, as a high pressure moves into the region, temperatures will cool down into the upper 70s to mid 80s from the area with mainly sunny skies lasting through next weekend before the heat returns.

Tomorrow's Outlook:

The cold front will already have cleared the area by tomorrow afternoon, with a WNW/northwest wind returning along with lower humidity, but the temperatures won't cool down as quickly. 850 mb temperatures are still expected to be near 16 degrees celsius, bringing temperatures into the mid to upper 80s from NYC and further west with a few lower 90s in the immediate NYC area. With a WNW/NW wind expected, Long Island and southern Connecticut will warm up as well, with widespread mid to upper 80s along with a few lower 90s in parts of Long Island. Mostly sunny skies are expected with no rainfall.

Thursday - Sunday: Sunny, Mild

A high pressure will move into the region on Thursday, bringing mainly sunny skies and seasonably mild temperatures, reaching the upper 70s to lower 80s in Long Island and southern Connecticut, and the lower to mid 80s from NYC and further west. Over the weekend, slightly more cloud cover is expected with slightly warmer temperatures from NYC and further west, reaching the mid to upper 80s, but with a south/SSE wind expected, Long Island and southern Connecticut will continue to see slightly cooler temperatures. An isolated shower or storm may be possible over the weekend, but at this time the risk of rain is very low and was not mentioned in the 5-Day Forecast.

Longer Range:

Next weekend, another massive ridge will build in the central US, a region where excessive heat has been quite frequent so far this summer. As we have seen so far this summer, the worst of the heat will stay to the west of the region, and the heat will spread into the region in a moderated form around early next week, but temperatures will still warm up, likely reaching the 90s again in parts of the area on Monday and Tuesday.

A cold front is expected to approach the region around Tuesday, but what happens afterwards is more uncertain. The latest models take the storm well into Canada, north enough to fail to bring any significant cool down into the region. As a result, some models, most notably the ECMWF, show heat lasting and intensifying through the rest of next week. The models have shown many heat potentials in the longer range before backing away as they approach the shorter range this summer, and it is very possible that the same happens in this case, which would likely bring a scenario where we see a hot start to next week followed by a cool down and another surge of heat, potentially stronger, by late next week. The set up currently indicated by the models is more supportive of stronger and longer lasting heat than the last several potentials, however, and the hot scenario cannot be ruled out completely and will be watched in case it becomes more likely. Stay tuned for more information on the longer range.

Monday, July 11, 2011

As a warm air mass began to spread into the region, today brought warmer temperatures into the area, with partly sunny skies and highs reaching the upper 80s to lower 90s inland, lower to mid 90s in the immediate NYC area, and the mid 80s to lower 90s in Long Island and southern Connecticut. The worst of the heat will take place tomorrow, when temperatures may reach the upper 90s in parts of NE NJ with the heat index reaching the lower 100s due to humid conditions, but behind tomorrow's cold front, pleasant weather conditions will return, with sunny skies lasting from Wednesday through next Monday along with seasonable temperatures.

Tomorrow's Outlook:Tomorrow will bring partly sunny skies to the area with a WSW wind turning WNW and 850 mb temperatures near 18-20 degrees celsius. The factors above support temperatures reaching the lower to mid 90s across northern NJ, SE NY, and NYC, and if mostly sunny skies continue through the afternoon and evening hours with no storms, temperatures may even reach the upper 90s in parts of NE NJ. With the wind direction coming mostly from the west, little sea breeze is expected in Long Island and southern Connecticut, with temperatures reaching the lower 90s across most of Long Island and southern Connecticut except for the immediate coast.

The cold front will move through tomorrow in the evening hours, but at this time, it appears that a relatively dry frontal passage is the more likely scenario. Isolated thunderstorms are possible in the afternoon hours, and any storm that develops may become strong or potentially severe, but the severe weather risk for tomorrow is low.

Wednesday And Beyond: Sunny, Dry, Seasonably MildBehind tomorrow's cold front, a stretch of pleasant weather will begin as a high pressure sticks around the region through the late week and the weekend, with mainly sunny skies and temperatures in the upper 70s to mid 80s from Thursday through Sunday, with the exception of Wednesday which should bring temperatures into the mid to upper 80s across most of the area with a few lower 90s possible in the immediate NYC area. Overnight lows will also be chilly, dropping into the 50s north and west of NYC and in southern Connecticut.

By early next week, unsettled weather begins to return into the region. Another potentially massive ridge in the central US once again appears to fail to bring a major heat wave in the area, with the worst of the heat staying to the west of the region, but temperatures will begin to warm up as the high pressure exits the region, bringing more of a SSW wind, and some of the heat in the central US spreads into the region, potentially bringing temperatures into the 90s for parts of the area around early-mid next week, which is also when the next chance of rain will be for the area. Stay tuned for more information on the longer range.

Sunday, July 10, 2011

With a high pressure near the region, today brough mostly sunny skies to the area once again, with high temperatures reaching the mid 80s inland, upper 80s in most of the immediate NYC area, and the lower 80s across most of Long Island and southern Connecticut. With a warm air mass moving into the region, temperatures will warm up throughout the next two days, with Tuesday expected to bring a heat index near 100 degrees in the immediate NYC area along with a risk of strong thunderstorms, but behind the cold front, a high pressure will move into the region, bringing a four day stretch of sunny skies and seasonable temperatures from Wednesday through next weekend.

Tomorrow's Outlook:A warm air mass currently over the central US will begin to spread towards the region, with 850 mb temperatures expected to reach 18 degrees celsius over the area. With mostly sunny skies and a southwest wind, this will bring temperatures into the upper 80s to lower 90s from NYC and further west. Due to the southwest wind, temperatures will be more variable east of NYC, ranging from the lower 80s near the southern/eastern sections of Long Island to the lower 90s in southern Connecticut away from the immediate coast. Parts of western Long Island may also reach the lower 90s.

Tuesday - Friday: Hot And Stormy, Then Sunny And DryThe peak of the heat is expected to arrive on Tuesday, when 850 mb temperatures will be near 20 degrees celsius along with WSW winds. The cold front will also be moving through the region on Tuesday, however, bringing a risk of thunderstorms to the region, and the amount of cloud cover and storms near the area will determine how hot temperatures get across the area. If the area sees partly sunny skies with isolated storms, high temperatures should reach the mid 90s in the immediate NYC area with the heat index reaching the lower 100s. If the area sees mostly cloudy skies with widespread storms, however, temperatures will end up lower, peaking in the lower 90s at most in the immediate NYC area.

At this time, I am leaning towards the warmer scenario, expecting mid 90s in NE NJ and lower 90s for most locations west of NYC, with scattered thunderstorms. Storms that develop on Tuesday may end up becoming strong, producing gusty winds. Stay tuned for more information on Tuesday's heat and potential storms.

Behind Tuesday's cold front, a high pressure will move into the region, providing the area with sunny skies and cooler temperatures from Wednesday through Saturday. Wednesday will still be warm, with upper 80s in NE NJ, but Thursday through Saturday will bring high temperatures in the upper 70s to mid 80s across the area. Temperatures will begin to warm up by Sunday/Monday.

Saturday, July 9, 2011

As a low pressure started to develop close to the area yesterday, widespread showers and thunderstorms affected the region, including the NYC tri-state area. While the more widespread heavy rainfall amounts stayed to the south of the area, parts of the area saw locally heavy rainfall as well, with radar estimates showing amounts locally from 1 to 3 inches from NW NJ into SE NY and central Connecticut. Otherwise, most of the area saw 1/4 to 1/2 inch of rain.

With the low pressure out of the region, currently moving towards Newfoundland, today ended up with warmer temperatures than those of yesterday but without any significant heat, as temperatures reached the mid 80s inland and the mid to upper 80s in the immediate NYC area, Long Island, and southern Connecticut. Tomorrow will bring similar temperatures, but a brief yet intense heat spell will affect the area on Monday and Tuesday, with the potential for temperatures to reach the 95-100 degree range in parts of the immediate NYC area on Tuesday along with a risk of strong thunderstorms.

Tomorrow's Outlook:

Tomorrow will be another nice day across the area. With a high pressure still over the region, mainly sunny skies will continue through tomorrow with a light south wind expected. High temperatures will be slightly warmer than those of today, reaching the mid to upper 80s inland, upper 80s to lower 90s across most of the immediate NYC area except for coastal sections of NYC, and the lower to mid 80s across most of Long Island and southern Connecticut, with the warmest temperatures away from the immediate coast.

Monday - Tuesday: Hot, Humid, And StormyOver the last week, the potential was mentioned for a surge of heat early this week that could bring temperatures into the lower to potentially mid 90s. Yesterday's storm, which is currently moving towards Newfoundland, will fail to prevent this heat from reaching the region, with its only impact on the area being slightly delaying the entrance of the heat. As we have been under the same pattern through most of the summer, this surge of heat will be short lasting as well, as a storm moving from west to east in southern Canada will already bring a cold front through on Tuesday, but despite the short duration of the heat, hot temperatures are expected, which could end up close to those of the early June heat wave.

As previously mentioned, a weak low pressure is expected to move from west to east through southern Canada, ending up north of the Great Lakes on Monday and north of Maine on Tuesday. As this is a weak storm, most of the heat will shift towards the east as well without significantly weakening. The June 6-8 heat wave set up was also similar to this set up in some ways, as there was also a weak low pressure in southern Canada moving from west to east, allowing the heat to spread into the region without any significant moderation. With the heat moving into the region, Monday will bring warmer temperatures, reaching the upper 80s to mid 90s from NYC and further west along with partly sunny skies. An isolated thunderstorm cannot be ruled out west of NYC in the afternoon, but no significant storms are expected on Monday at this time.

The cold front will move through the area on Tuesday. With the previous update, there was some uncertainty with the exact timing, and as a result, I went conservative with the temperature outlook. With the latest expected scenario, however, it appears that the timing and cloud cover will be supportive enough to allow temperatures to rise into the 90s across parts of, if not most of the area. Lower to mid 90s are expected from NYC and further west on Tuesday, and a few upper 90s cannot be ruled out in parts of NE NJ should the warmer case scenario verify. Humid conditions are expected as well, and the heat index could reach the upper 90s to near 100 degrees on Tuesday. Scattered thunderstorms are possible once again in the afternoon and evening hours, with the potential for strong to severe thunderstorms as well.

Mid-Late Week: Sunny, Dry And ColderA trough will move into the region behind Tuesday's cold front, bringing a relief from the brief heat spell. While Wednesday should still be very warm, with mid to upper 80s across most of the area with a west/WNW wind expected, the rest of the week will be colder as a high pressure moves over the region, bringing a cooler air mass along with sunny skies. Low temperatures on Wednesday night are expected to drop into the 50s away from NYC and the coastal areas, with sunny skies and highs in the upper 70s to mid 80s expected on Thursday. Similar conditions are expected for Friday as well.

By next weekend, another large ridge in the central US should begin to spread towards the region. The worst of the heat could stay to the west of the region once again as it has done so far this summer, but hot temperatures are likely to return into the region once again by the weekend, and temperatures may return into the 90s in parts of the area by the weekend or early next week. Stay tuned for more information on the longer range.

Thursday, July 7, 2011

Note: The 5-Day Forecast will be posted tomorrow in the early morning. Storm updates may be posted tomorrow morning and afternoon, but otherwise, the next full update will be posted on Saturday night.

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The area saw its fourth consecutive day of heat as temperatures surged into the upper 80s to lower 90s inland, lower to mid 90s in most of the immediate NYC area, and mostly in the mid 80s to lower 90s across Long Island and southern Connecticut. Earlier this afternoon, isolated thunderstorms formed in the southern half of New York City and moved east through southern Long Island, but otherwise, most of the area stayed dry.

Since my discussion three days ago about the potential for the models to trend towards adding a feature to block the heat from easily spreading in, the models trended towards a low pressure moving towards Nova Scotia/Newfoundland and Greenland during the weekend, shortening the heat to a 2 day time frame, around Monday and Tuesday. As the low pressure will develop near the region tomorrow, however, this trend put the area under the risk of locally heavy rainfall tomorrow and tomorrow night, with occasional showers and thunderstorms bringing the potential for rain totals locally as high as 1 to 2 inches of rain.

Tomorrow's Outlook:As previously mentioned, a low pressure will begin to develop near the region tomorrow, which will later on become a stronger storm moving towards Nova Scotia and Newfoundland. This low pressure will not be very organized yet tomorrow, but it will produce scattered showers and thunderstorms, which will be capable of producing locally heavy rain with precipitable water values near 2 inches. It is possible that some places in the tri-state area may fail to see rain, but at this time, the coverage area of the rain is expected to be widespread enough to affect at least most of the area. Due to the cloud cover and rain, tomorrow will bring cooler temperatures, peaking in the mid 70s to lower 80s across the area. Storm updates may be posted tomorrow in the morning and afternoon hours.

Weekend To Early Next Week: Warming Up

A few days ago, on July 4th, the models were expecting a transition to a positive NAO with a large surge of heat spreading into the region. My update that afternoon mentioned that the models have done the same for this week and ended up trending towards a negative NAO and a low pressure near the Davis Strait, keeping any heat surge relatively weak and preventing it from becoming sustained. We are seeing the models repeating this trend, as the latest consensus is there for the low pressure which will form near the region tomorrow to move towards Newfoundland and then towards Greenland. While it is unlikely to move into the Davis Strait as the last few storms in that region have done, a negative NAO will persist, and is expected to remain mostly negative or neutral through mid July.

With the storm moving into the Newfoundland/Greenland region, the entrance of the heat into the region will be delayed, with lower 90s expected to make an appearance in parts of the area on Monday and potentially Tuesday. Mid to upper 80s are expected from NYC and further west on Sunday, with parts of NE NJ potentially reaching the 90 degree mark. With a high pressure nearby, mostly sunny skies are expected for Sunday and Monday.

By Tuesday, a storm moving from west to east through southern Canada will bring an end to the short lasting surge of heat. The cold front will move through around Tuesday, and while the exact timing is still uncertain, there is the potential for thunderstorms with this cold front, especially around Monday night and potentially on Tuesday if the cold front slows down from the current expectation.

Longer Range: Cool Down, Then Warming Up

Behind the front, the pattern we are currently under will repeat itself once again, as the models have trended away from the original idea of a longer lasting heat spell lasting through next week and now show a trough moving into the region. This will not bring a much colder air mass, but temperatures are expected to cool down into at least the upper 70s to mid 80s through mid-late next week with mainly sunny skies. There are indications that the area may warm up once again by next weekend, but the specific details cannot be nailed down yet as this is still in the longer range. Stay tuned for more information on the longer range.

Due to technical difficulties, no update was posted last night. I am currently working on a detailed update which will be posted this afternoon, discussing widespread thunderstorms on Friday and Friday night, the return of hot temperatures on Monday and Tuesday early next week, and what may follow in the longer range.

Tuesday, July 5, 2011

The 5-Day Forecast page was updated today for the immediate NYC area and the interior areas. The forecast for Long Island and southern Connecticut will be completed and posted by tomorrow morning.

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Wednesday And Thursday: Heat ContinuesA weak low pressure moving through the Northeast will help keep the heat in place through tomorrow and Thursday. Tomorrow will be the hottest day, with a warm southwest wind bringing temperatures into the upper 80s to lower 90s across most of the area with a few mid 90s in the immediate NYC area. Long Island will be the coolest spot, with high temperatures ranging from the lower 80s further south/east to the upper 80s further north/west and closer to NYC.

A cold front will move through the region, but unlike yesterday's expectation, the cold front is now expected to be mostly dry when it reaches the area. Isolated thunderstorms are expected, some of them producing locally heavy rainfall, but they will not be as widespread or as heavy as Sunday's storms. As a result, Thursday's temperatures were raised with less cloud cover in the forecast, with temperatures now expected to end up similar to those of Wednesday, if not slightly cooler.

Friday And Beyond: Slightly Cooler, Then Warm AgainBehind the cold front, a cooler air mass will move into the region for Friday and Saturday, bringing high temperatures into the upper 70s to mid 80s across the area for both days with mostly sunny skies and dry conditions, though an isolated thunderstorm cannot be ruled out for Friday especially south and east of NYC.

For Sunday through Tuesday, the models continue to show heat spreading into the region, but vary with the intensity and duration of the heat. As I mentioned in my post last night, a more likely scenario based on this summer's trend and pattern is one where the area slightly warms up for 2-3 days around early next week, likely somewhere in the upper 80s-mid 90s range, followed by a cold front with a cooler air mass briefly returning behind it. This is still in the longer range and could change, but at this time, this scenario is more likely than a prolonged heat wave with temperatures surging into the upper 90s. More information will be posted on this time frame as details become clearer.